Elastic modulus and thermal conductivity of ultradrawn polyethylene

The axial and transverse Young's modulus and thermal conductivity of gel an d single crystal mat polyethylene with draw ratios lambda = 1-350 have been measured from 160 to 360 K. The axial Young's modulus increases sharply wi th increasing lambda, whereas the transverse modulus shows a slight decreas e. The thermal conductivity exhibits a similar behavior. At lambda = 350, t he axial Young's modulus and thermal conductivity are, respectively, 20% an d three times higher than those of steel. For this ultradrawn material both the magnitude and the temperature dependence of the axial Young's modulus are close to those of polyethylene crystal. The high values of the axial Yo ung's modulus and thermal conductivity arise from the presence of a large p ercentage (similar to 85%) of long needle crystals. (C) 1999 John Wiley & S ons, Inc.